Marsh Concrete Rainbow Arch Bridge
Encyclopedia
Marsh Concrete Rainbow Arch Bridge is a reinforced concrete
through arch bridge over the Little Cottonwood River
in Cambria Township
, Blue Earth County, Minnesota
. The bridge is listed on the National Register of Historic Places
. The bridge no longer carries traffic; it has since been shifted to another bridge to the east.
The bridge was designed by James Barney Marsh
and built in 1911, the same year in which he filed a patent
for his rainbow arch design. His design features two arched ribs, one on either side of the roadway, rising above the deck
. The deck is suspended from the arches by vertical risers. Drivers see the rainbow arch crowns on each side, similar to crossing a pony truss bridge. The bridge over the Little Cottonwood River is one of the oldest Marsh rainbow arches in the country. Unfortunately, as traffic flow increased and farm machinery got larger, many of Marsh's rainbow arch designs became obsolete, since they could not be widened. There are only half a dozen Marsh rainbow arch bridges remaining in Minnesota.
Reinforced concrete
Reinforced concrete is concrete in which reinforcement bars , reinforcement grids, plates or fibers have been incorporated to strengthen the concrete in tension. It was invented by French gardener Joseph Monier in 1849 and patented in 1867. The term Ferro Concrete refers only to concrete that is...
through arch bridge over the Little Cottonwood River
Little Cottonwood River
The Little Cottonwood River is a tributary of the Minnesota River, 83 miles long, in southwestern Minnesota in the United States...
in Cambria Township
Cambria Township, Minnesota
Cambria Township is a township in Blue Earth County, Minnesota, United States. The population was 271 as of the 2000 census.-Geography:According to the United States Census Bureau, the township has a total area of , of which is land and is water...
, Blue Earth County, Minnesota
Blue Earth County, Minnesota
Blue Earth County is a county located in the U.S. state of Minnesota. As of 2010, the population was 64,013. Its county seat is Mankato.Blue Earth County is part of the Mankato–North Mankato Metropolitan Statistical Area.-Geography:...
. The bridge is listed on the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
. The bridge no longer carries traffic; it has since been shifted to another bridge to the east.
The bridge was designed by James Barney Marsh
James Barney Marsh
James Barney Marsh was an engineer and bridge designer born in North Lake, Wisconsin. He was a graduate of Iowa State College of Agriculture and Mechanical Arts in Ames....
and built in 1911, the same year in which he filed a patent
Patent
A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....
for his rainbow arch design. His design features two arched ribs, one on either side of the roadway, rising above the deck
Deck (bridge)
A bridge deck or road bed is the roadway, or the pedestrian walkway, surface of a bridge. It is not to be confused with any deck of a ship.The deck may be of concrete,wood which in turn may be covered with asphalt concrete or other pavement...
. The deck is suspended from the arches by vertical risers. Drivers see the rainbow arch crowns on each side, similar to crossing a pony truss bridge. The bridge over the Little Cottonwood River is one of the oldest Marsh rainbow arches in the country. Unfortunately, as traffic flow increased and farm machinery got larger, many of Marsh's rainbow arch designs became obsolete, since they could not be widened. There are only half a dozen Marsh rainbow arch bridges remaining in Minnesota.